Final Fantasy VII, basically.
Before that, I was solidly in Nintendo's camp, even though I'd gotten bored with the SNES. There were far too many platformers and beat 'em ups for my taste and not enough Zelda and FF VI type experiences. When the Playstation 1 first came out, I'd drifted far enough away from gaming that it didn't really grab me.
Until I saw the FF VII commercial for the first time. Talk about jaw-dropping. FF VII had been my undisputed favorite game ever, so of course that was a BIG incentive to check out the PS1. After that was Final Fantasy Tactics, Suikoden I & II, Gran Turismo, and the games just kept coming. I will always consider the PS1 as my true awakening as a gaming enthusiast.
The PS2 was kind of a no-brainer. By the time I got one, it was already the champ. I got a DreamCast, too, and loved it, but it didn't have enough games to really threaten the PS2's prime position in front of the television.
The PC and MMOs stole me away at the start of last gen. I ignored consoles. When my best friend and MMO gaming buddy passed away, I didn't have the heart for any of the online games we'd played anymore. I looked into all three consoles from a fairly neutral perspective and--this is kind of embarrassing to say--The Last Guardian was one of the deciding factors in getting a PS3. Of course, Gran Turismo was the other big factor, so that's okay.
